1. Field of the Invention
The present invention pertains to an optical device for the simultaneous detection of cardiac and respiratory movements and to the use of the device for synchronizing nuclear magnetic resonance imaging instruments, more commonly known as MRI instruments.
2. Description of the Prior Art
In prior art methods, the quality of the images given by these devices is improved by synchronizing them with the heart and respiratory rhythms of the patients examined, by means of signals from electrocardiographs.
However, the electrodes and metallic connecting cables used to convey the synchronizing signals deform the field lines of the powerful magnetic and electrical fields radiated, and the quality of the images obtained is affected. This results in a major disadvantage for physicians who risk making false diagnoses.
In an alternative embodiment of the method described above, the synchronization is done with signals from acoustic and pneumatic stethoscopes. These stethoscopes have the advantage, when compared with electrocardiographs, of not interfering with the magnetic and electromagnetic fields. But they remain sensitive to ambient acoustic noise, and the propagation time of the pressure wave in the connecting tubes which link them to the MRI instruments results in a phase shift, incompatible with its function and difficult to compensate for, between the synchronizing signals and the corresponding cardiac and respiratory activities.
3. Summary of the Invention
An object of the invention is to remove the above disadvantages.
To this end, an object of the invention is an optical device for the simultaneous detection of heart and respiratory movements, a device comprising a sensor with a movable mirror coupled to means used to shift the mirror by the patient's heart and thorax movements, a light generator to illuminate the mirror and electro-optical means to convert the intensity of the light beams reflected by the mirror into an electrical signal.